I'm having a problem with reverse gear: whenever i put the car into reverse, even from start-up, it crunches the gears. The only way I can avoid it is to heavily apply the brake pedal, but even this doesn't always work.

Thoughts?

sounds like the clutch is on its way out or needs adjusting

Agreed; check the clutch adjustment.

Cool, will get it checked. Thanks.

What if you engage first move the car forward slightly and then enage reverse?

That actually addresses a different problem, where the reverse gear teeth are meeting each other tooth to tooth rather than engaging. It's possible, but not likely, if the gear is grinding as described rather than making a single click on engagement. It's not like adjusting a cable clutch takes long once you understand the free play or pedal travel required. It took a wee while on my Xantia, but more of that was to do with removing and replacing the standard airbox and duct than with adjusting the clutch.